arachnoid, a. and n.
(əˈræknɔɪd)
[ad. mod.L. arachnoīdes, a. Gr. ἀραχνο-ειδής cobweb-like: see -oid.]
A. adj.
1. Bot. Covered with or formed of long, delicate, cobweb-like hairs or fibres.
| 1857 Berkeley Cryptog. Bot. §401 An arachnoid or woven veil attached to the edge, and sometimes entirely covering the gills. 1874 M. C. Cooke Fungi 91 Arachnoid threads. |
2. Phys. Of or pertaining to the arachnoid. (See B.)
| 1789 Loiterer 26 Sept. No. 35, p. 9 The dura and the pia Mater, and the arachnoid coat, entirely consisted of the Wings of Moths. 1836–39 Todd Cycl. Anat. & Phys. II. 278/1 The chamber is lined by the arachnoid membrane. 1872 Huxley Phys. xi. 249 It secretes..the arachnoid fluid. |
3. Ent. Resembling the Arachnida.
| 1852 Dana Crust. i. 14 The Arachnoid type, as in Nymphon. |
B. n. The delicate serous membrane or membranous sac lining the dura mater, and enveloping the brain and spinal cord.
| [1751 Chambers Cycl., Arachnoides..a fine, thin, transparent membrane..supposed to invest the whole substance of the brain, medulla oblongata, and spinal marrow.] 1839–47 Todd Cycl. Anat. & Phys. III. 638/1 The arachnoid covers the superior surface of the cerebellum. |